Raikkonen's most previous win had been with Lotus at the season-opening Australian Grand Prix in 2013. He'd driven his Ferrari to three second-place finishes this season before Sunday's victory.
Hamilton leads Vettel by 67 points and any result Sunday that puts him eight or more points ahead of Vettel clinches the title.
If Hamilton wins Sunday, Vettel must finish second to push the championship another week to Mexico City.
Mick Schumacher won eight of the last 15 races in F3 this season and said this week he will announce his future race plans soon.
Starting from pole, the Mercedes driver was never seriously challenged and crossed the finish line 12.919 seconds ahead of teammate Valtteri Bottas.
Lewis Hamilton claimed pole position for the Japanese Grand Prix on Saturday, leading a 1-2 finish for Mercedes and taking a step closer to securing his fifth F1 title.
With five races to go, Hamilton would move a step closer to winning a fifth world championship with a win in Suzuka, a race he has dominated in recent years.
Hamilton now leads Ferrari's Sebastian Vettel by 50 points in the standings with five races remaining as both chase their fifth title.
Bottas was 0.145 ahead of Hamilton and 0.56 ahead of third-placed Sebastian Vettel, who is second in the standings, 40 points off Hamilton.
Hamilton was .199 seconds faster than Bottas in cool, overcast conditions, followed by the two Red Bulls of Max Verstappen and Daniel Ricciardo.
It's the second season in a row that Vettel has started strongly only for Hamilton to surge in the second half.
While the Formula 1 teams and drivers get all the attention, working tirelessly behind the scenes during every race is Tata's talented team on track and as well personnel back at its UK base.
It is looking increasingly like a repeat scenario for the Ferrari driver, who now has just six races left to catch Hamilton as they both bid for a fifth F1 title.
Vettel sat glum-faced in the news conference after qualifying third, trailing Hamilton by a sizeable margin in Formula One terms: 0.6 seconds.
Hamilton produced something special to set a blistering time and secure a record-extending 79th pole position in Formula One and a 200th for a British driver.
The 38-year-old Raikkonen, the 2007 Formula One champion, is being replaced next season by 20-year-old Charles Leclerc.
Sebastian Vettel was nearly two seconds behind Raikkonen in ninth, but was using slower tires than his teammate.
Raikkonen, who won the 2007 Formula One title with Ferrari, will be heading back to Sauber from next season while Leclerc will take his seat alongside Sebastian Vettel.
Vettel and Hamilton are both chasing a fifth F1 title to move level with Argentine great Juan Manuel Fangio and go two behind record-holder Michael Schumacher.
The Mercedes driver beat Raikkonen, who had started in pole, to tie Michael Schumacher's record of five Italian GP victories and extend his championship lead.
Surprisingly, it was Kimi Raikkonen who edged his teammate and title hopeful Vettel in qualifying on Saturday to clinch only his second pole position in 10 years.
Hamilton started from pole position for a record fifth time at Spa, and a record-extending 78th in Formula One, with Vettel second on the grid.
The Mercedes driver saved his best for the last lap to easily beat Sebastian Vettel's leading time for Ferrari by 0.7 seconds and secure a Formula One record-extending 78th pole.
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